In recent years, in radio communication, specifically, in mobile communication, various data such as image and data in addition to voice are targets for information transmission. Requests for high-speed transmission are anticipated to increase further in the future, and, to perform high-speed transmission, radio transmission techniques of using limited frequency resources efficiently and realizing high transmission efficiency are required.
One of techniques capable of responding to such requests is orthogonal frequency division multiplexing (OFDM). It is known that OFDM is a multicarrier transmission technique that transmits data in parallel using a number of subcarriers, has features including high frequency efficiency and reduced inter-symbol interference under the multi-path environment, and is effective to improve transmission efficiency.
When data for a plurality of radio communication mobile station apparatuses (hereinafter simply “mobile station”) is frequency-multiplexed with a plurality of subcarriers,performing frequency scheduling is considered using this OFDM on the downlink (see Non Patent Document 1).
In frequency scheduling, a radio communication base station apparatus (hereinafter simply “base station”) adaptively allocates subcarriers to respective mobile stations according to the received quality per frequency band of each mobile station, so that it is possible to obtain maximum multi-user diversity gain and perform communication quite efficiently. This frequency scheduling is suitable to data communication where the mobile station moves in a low-speed.
For acquiring multi-user diversity gain efficiently, the bandwidth for resource blocks needs to be set narrower than correlation bandwidth of channel response with respect to communication systems. However, if the bandwidth for resourceblocks is set narrower, the number of bits that can be transmitted per resource block decreases. Here, the resource block is the band of one subcarrier or a band grouping severalsubcarriers, and is a control unit of frequency schedulingand adaptive control.
Here, in error correcting encode such as turbo code, if the number of bits that can be transmitted per resource block decreases and the encoding block size becomes smaller, the error correcting performance is significantly degraded. Then, a technique is proposed for determining the size of encodingblock size to maximize the error correcting performance, dividing encoded transmission data into a plurality of resource blocks and transmitting these when frequency schedulingis performed using error correcting encoding, (see Non Patent Document 2). With this technique, error correcting encoding is performed for all of a plurality of resource blocks at the same coding rate, sequentially, the encoded data is divided into a plurality of resource blocks and the modulation scheme is adaptively controlled for each resource block according to the received quality.    Non-Patent Document 1: R1-050604 “Downlink Channelization and Multiplexing for EUTRA” 3GPP TSG RAN WG1 Ad Hoc on LTE, Sophia Antipolis, France, 20-21 Jun., 2005    Non-Patent Document 2: R1-050590, “Physical Channels and Multiplexing in Evolved UTRA Downlink”, NTT DoCoMo, 3GPP TSG-RANWG1, 2005/06